Numerous rotary components, such as rotors, spools and handle shafts, that rotate relative to the reel body or against other components are employed in fishing reels such as spinning reels and dual-bearing reels. Support on bearings lets rotary components of this sort rotate in the reel body or against other components. Ball bearings are often used in fishing reels as the bearings that support these rotary components.
Because fishing reels are generally used in an atmosphere in which moisture clings to and is liable to corrode ball bearings, improving their resistance to corrosion is desirable. Rust-withstanding stainless steels have been used conventionally to improve the corrosion resistance of ball bearings, especially as the material for ball bearings employed in fishing reels used for ocean fishing.
Taking rotational performance and cost into consideration, among the stainless steels, grade SUS440C (JIS), which can be hardened, is often employed for the rolling bodies in ball bearings. That is, SUS 440C sustains high rotational performance because it is sufficiently high-strength and impact-resistant for bearing applications, and maintains high machining precision. Nevertheless, a problem with SUS440C is that, compared to austenites such as grade SUS304 and SUS316 among carbon steels, though it is harder its corrosion resistance is lower. Therefore, if SUS 440C is to be employed for the rolling bodies in a ball bearing, the bearing as a unit should have a water-resistant structure in order to prevent corrosion. To lend the bearing a water-resistant structure, rubber-seal type ball bearings in which a sealing element made of rubber is fitted in between the inner and outer races, contacting both, are often used. The sealing element in rubber-seal type ball bearings is fitted at least on the ball-bearing side where liquids invade.
Preventing corrosion with a sealed bearing will mean that the sealing element contacting the inner/outer races places a higher rotational load on the bearing, which degrades rotational performance. To sustain rotational performance a non-contact sealing element could be employed, but sealing performance is poor with bearings having non-contacting sealing elements, and in fishing reels for ocean fishing in particular, corrosion resistance is not sufficient.
Meanwhile, disposing the seal element on the side of the bearings where the reel is subject to invasion by liquids is effective for preventing corrosion. Nevertheless dousing the reel with water from a hose to wash it after having ocean fished, for example, will not rinse the bearings, since water will not permeate to the bearing. Of course, rinsing the bearings is possible if the seal is not provided, but that risks corrosion and caustic erosion of the reel interior components arising when the washing water forces inside the reel salt deposits remnant on the exterior.